Aerobic, anaerobic and combination estimates of cerebral hypoperfusion during and after cardiac surgery

We studied 15 patients undergoing cardiac surgery involving hypothermic car diopulmonary bypass (CPB). Cerebral arteriovenous difference in oxygen cont ent (AVDO(2)) was significantly less during CPB and for up to 18 h after op eration compared with pre-CPB values (P<0.05). There were no significant ch anges in mean jugular bulb oxyhaemoglobin saturation (Sjv(O2)), cerebral ar teriovenous difference in lactate content or lactate-oxygen index (LOI). Sj v(O2) and arterial carbon dioxide tension (Pa-CO2) (P=0.005) were positivel y correlated as were AVDO(2) and haemoglobin concentration (P=0.012). AVDO( 2) and Pa-CO2 (P=0.007) were negatively correlated as were LOI and arterial oxyhaemoglobin saturation (P=0.037). There were no significant correlation s between mean arterial pressure and any of the variables. Sjv(O2), and AVD O(2) may require correction for changes in Pa-CO2 and haemoglobin concentra tion before relating these variables to cerebral outcome.